Waste products present expensive disposal problems to the industries that generate them. Unprocessed waste products typically cannot be disposed of in landfills due to regulations on water content. Even with more permissive regulations, it is much more expensive to transport and dispose of unprocessed waste products than just solid components because transportation charges correspond to weight.
Additionally, the scope of potential uses of such waste products is often substantially increased by removal of the liquid component from the solid component. Typically, the value of the dry solids arises from the decrease in weight occasioned by the removal of the liquid fraction, which leads to decreased disposal and transportation costs. Additionally, the recovered dried solids may be commercially valuable, such as if they are useable in other industrial applications (e.g., as filler in concrete mixtures) or can be sold in secondary markets, such as in the case where the waste products comprise coal or mineral slurries.
Unfortunately, efforts to work around the waste disposal problems often employ methods lacking environmental soundness. For example, many industries dump waste products, such as sludge, into holding ponds, which are typically enormous concrete or plastic lined, man-made pools. The waste products then sit in these sludge ponds while the solid materials settle at the bottom over time with the aid of only gravity. Aside from being a slow process, the potential for the pool lining to fail to fail or result in contamination of the surrounding environment makes this a less-than-desirable solution in terms of both efficiency and environmental impact.
Industrial sludge ponds suffer from significant practical difficulties. To begin, sludge ponds have a poor resulting yield (dry solid percentage content). Being passive, it also takes a long time to separate water from solids for a given volume of sludge, as compared to devices that rely on active separation. Keeping up with the output for any given waste flow rate requires a greater area than if active separation systems are used. However, most active separation are expensive to make and are not readily scaled up or down to handle corresponding volumes of industrial waste flow rates. The lack of portability is also a significant limiting factor.
Accordingly, a need is identified for fast and efficient methods and devices for actively separating water from a waste product, and also to produce a resulting solid that is sufficiently dry for use in other applications.